What is Non-Volatile Memory?

Non-volatile memory is any sort of computer memory system that stores data without power, which is to say that it doesn’t need to be connected to a power source to access its critical information. If power is interrupted or the computer is shut down mid-project, data stored this way won’t be lost. Common examples include read-only memory (ROM) applications and optical media like CDs and DVDs; flash drives and usually even parts of computer hard drives are structured this way, too. The biggest advantages to this sort of memory are convenience and ease of storage, while costs and the potential for data to be erased or written over can be cons. Technology changes can also make certain devices or means of accessing data obsolete, though in most cases the information is there — it’s just that getting to it can be a challenge.

Computers and computer-driven technologies usually have a couple of different ways of storing data and information, and these are often referred to as “memory.” Non-volatile memory is some of the most permanent, but in most cases it is also secondary, which is to say that it is a copy of information that already exists somewhere else in some other form. It isn’t usually intended as a “backup,” but in some cases it is used this way.

Most technology experts think about this sort of memory in juxtaposition to what it’s not. It’s not temporary, and it doesn’t need to be powered in order to keep its integrity. This puts it in direct opposition to random-access memory (RAM), which is the sort of memory a computer uses to immediately display and capture things that are happening in real time. If the computer loses power, this information usually disappears. It often can’t be retrieved unless it was saved to a non-volatile source like a hard drive, a flash drive, or a CD-ROM.

Read-Only Memory, also called mask ROM, is one of the most popular types of non-volatile storage. It holds information permanently in a means that cannot be erased from the chip. Several other non-volatile types of memory share the "ROM" acronym, but can actually be rewritten. These include Erasable Programmable ROM (EPROM), Electrically Erasable Programmable ROM (EEPROM), and flash memory, also sometimes called flash ROM. Most forms of EPROM are erased using UV light, which erases all data on the chip, while data on an EEPROM chip can be erased and rewritten selectively. Flash memory evolved from, and is similar to, EEPROM.

CDs and DVDs are also a form of non-volatile memory, storing their data in pits on the surface of the disks. They use optical technology as opposed to most other types of computer storage, which are typically magnetic based. This makes them exempt to certain problems faced by other forms of media, such as data loss caused by proximity to magnets. Optical disks, however, have their own set of problems, including scratching.

Non-volatile, secondary memory is usually seen as advantageous, though as with so many things there are both pros and cons. On the plus side, the devices used to capture it are typically less costly to produce than are those that channel volatile memory, and data can be stored for a really long time — sometimes indefinitely. In many cases these sorts of devices also make it possible for computer hardware to be upgradeable. This allows developers to both adjust to new technologies and stave off complete hardware upgrades.

Over time, users may find that not all of their information is as accessible as it once was thanks in part to changing technology. Some storage devices, particularly CDs and DVDs, can reasonably be expected to continue being accessed well into the future, but depending on the file type that’s stored access might be a problem. As computer software is updated, files written in or created by older versions of programs may not be readable. More antiquated storage devices like floppy disks and zip drives might also need special technology to access later on down the road.

The utility of non-volatile devices when it comes to long-term storage may also mean that they might not work as well as those that handle immediate memory, at least when it comes to delivering quick and consistent results. Volatile devices are usually better suited to memory that needs to be read and written over. It is generally more expensive than non-volatile memory, but is also much faster.